Impurity gettering techniques are widely used in the production of modern semiconductor devices to remove undesirable contaminants from active regions of the device. Gettering involves the transportation of the impurities to sink regions in the substrate that are located away from the active regions.
Structural defects in the crystalline structure of the substrate are commonly used as sinks for the gettering of contaminants. Gettering of this type is well-developed for silicon substrates, and includes two categories of gettering: intrinsic and extrinsic.
In intrinsic gettering, a region of the substrate containing precipitates such as SiO2 act as an effective sink region. Such a region contains many types of structural defects such as punched out dislocations and extrinsic stacking faults in addition to SiO2 precipitates. Generally, different types of structural defects have their own characteristics in the gettering of impurities
In extrinsic gettering, structural defects are created using external sources. For example, a common extrinsic gettering technique is to grind the back surface of the silicon wafer.